In a forming station for producing wood-fiber boards there is currently a need to distribute glue-coated wood fibers on a wire or a conveying belt to form a layer with a certain thickness. The layer of wood fibers is transported by the wire or conveying belt to a pressing plant, in which the wood fibers, under the influence of pressure and temperature, are pressed together into a continuous board.
As is shown in International Application No. PCT/SE95/01402, a device of the type described above is previously known, whose purpose is the leveling of the material web after air distribution of the particles. Another type of leveling or milling is disclosed in U.S. Pat. No. 5,496,570 and consists of a scraper or a planing device, which, for the method shown, cut off any excess of the wood fibers. A disadvantage with the known technique is that a large amount of wood fibers are recirculated to the process from the leveling or milling step, which. is unfavorable, since the quality deteriorates by wear.
U.S. Pat. No. 5,496,570 shows how a number of disc rollers are used for distributing wood fibers and for pulverizing possible clumps among the wood fibers. A similar device, for distributing wood fibers with the aid of disc rollers, is shown in Swedish Patent No. 436,627. A common element in both of these latter references is that the disc rollers are located above the level of the wood fibers and by utilizing successively different distances between the discs of the different disc rollers, one may achieve sorting and orientation of the wood fibers in several different layers. A disadvantage, however, is that the distribution is unsatisfactory across the material web.
An object of the present invention is to thus provide a homogenous layer of wood fibers, having a desired distribution over the width of the material web. Another object is to provide a distribution of the wood fibers, in such way that any considerable subsequent leveling or milling is thereby avoided.